Air Intake Pipe Size

Discussion in 'Air Intake / Exhaust' started by supersonicbug, Jun 26, 2010.

  1. supersonicbug

    supersonicbug New Member

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    I have install B18CR engine into my EJ and I plan to have open port filter set up in my car. Can someone let me know what would be the optimum air intake pipe diameter size that I should have it custom make? Would 3" or 3.25" or 3.5" be fine? Thanks.
     
  2. JDMJNKY

    JDMJNKY New Member

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    3" is fine!
     
  3. supersonicbug

    supersonicbug New Member

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    Thanks bro....
     
  4. JIMBOB-EK9

    JIMBOB-EK9 Moderator Donator

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    X2 :nice:
     
  5. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    My Comptech is 3.5"
    A 1.8 should go 3.5"
     
  6. JDMJNKY

    JDMJNKY New Member

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    DC5 is different from ek9 or dc2. Comptech for an ITR is 3.0 and 2.75 for b18c1 IIRC
     
  7. jason e-ek4

    jason e-ek4 New Member

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    Really? Are you sure. All the bits of information i've seen from different sources states that the Comptech intake pipe is 3.5 " in diameter.
     
  8. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    I have it for my ek9, it's 3.5". B18 is same.
     
  9. abunai888

    abunai888 V-tec Addict!

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    3'' even for b20 would be ok
     
  10. KieranEG6

    KieranEG6 Argumentative!! Donator

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    Thinking about this now! An engine is technicaly a big air pump with a by product of rotational power to the wheels.

    Soo surely the piping of the air into the engine should be relevant to the exhaust piping out, no??

    If the optimum pipe diameter of the exhaust is around 2.5" (61mm) then wouldnt the optimun piping to the intake be around 2.5" or maybe only slightly larger??

    Why have a big fat pipe full of air in the engine bay being heated up by the bay temps when it can only funnel into a 62mm trottle body?

    Im still unconvinced by the whole Whale willy J's racing style intake pipe for this reason.

    I would say a 3" pipe with a cone right in the corner behind the headlight with cold air feeds would be more than enough. Personaly id use 2.75 or less to try and keep more velocity in the air flow, depending on how much the engine was tuned. This is in relivents to a prity much std b18cR.

    As when you think about it the further away the filter and the bigger the piping the more work your engine has to do to suck that cold air into it and the longer it will take thus less power.

    Well thats my theory but it seems to make sense to me.
    Its prity much the same argument to why we dont all a have 3" exhaust systems as its not bigger = better factor its more what size will have optimum flow for the engine setup
     
    Last edited: Jun 30, 2010
  11. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    Your idea is correct.

    The reason why the intake valves are bigger than the exhuast valves, is because it takes more energy to intake air than it does to exhuast air.

    Intake piping should always be bigger than the exhuast piping so it puts less restriction on the air flow.

    HP is also a measure of air CFM. Maximum torque created at xx rpm is where cylinder fill(volumetric efficiency) is at peak %. The Intake, headers and exhuast choice combination is very very important. Not just because it has a 'toda' badge on it. Combination is the key.

    Anyway. I love my 3.5" comptech ice box with Twin velocity stacks.

    For a B16, generic 3" is enough.
     
  12. KieranEG6

    KieranEG6 Argumentative!! Donator

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    So are you saying the mugen airbox system that uses the std 2.75 intake pipe is restricting because it using a small pipe???

    Also to point out this is on a std B18CR not a b16

    I know what your saying about the intake valves being bigger but i think thats more down to the port shape and angle as the air is being vacumed in not forced out so different shaped port is optimum

    I dont see how a big 3.5" pipe up to a 2.5" throttle body will give gains or have more volumetric effeciency/ the optimum air velocity than a 2.75 pipe when the engine tuning is at its optimum with a 2.75 pipe.

    I mean yea if your running lots of head work and big cams the optimum intake air velocity with change thus needing maybe a larger intake piping and throttle body. But with out all that your just waisting your time an probably loosing power.
     
  13. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    The mugen use the standard rubber arm which does have ripples inside.

    When there's a combustion, energy is released and needs to go excavate, that's free energy, compare to when the air is intaken. This isn't my opinion, it's fact. It was even said so on a Honda video, I think it was omnimans 200whp b16a when he was talking about valves.

    There's a huge difference installing a 70mm butterfly TB compared to a tapered 60mm>70mm TB. On a 1.6 or 1.8, you'd loose power, with the tapered you gain power.

    The comptech system has a reducer when it connects the intake arm to the TB creating a tapered design. As well as the additional velocity stack at the end of the tube and a another massive stack at the end of the ice box.

    This intake was proven to make the most power compared to AEM and injen 3" cold intake pipe, peak and especially mid range torque and HP. Most of all, it generated the most gain per RPM.

    I chose this intake because it works on a 1.6 and give plenty of headroom for 1.8 or 2.0L.

    My power graph showed it developed max whp @ 9000rpm stock internals after tuning of course. I don't think I'm loosing power.

     
    Last edited: Jul 1, 2010
  14. KieranEG6

    KieranEG6 Argumentative!! Donator

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    The tuning of a 200hp b16 is a bit different as its a tuned motor so cams and managment are totaly different.

    I wasnt saying your intake system would loose power as your using a specific designed one. And to add to that you have mapped it to suit. On that note a std b18c with peak hp right up at 9000 doesnt sound very usefull to me. Just out of intrest can you show me were your intake system was proven to be the best or was that the best just over the AEM and Injen. Witch i have had both of an really didnt think much of on the road so i refitted my std system with a drop in and found the cars power curve to be much more usable.

    I was refering to for example you got a 3.5" tube with a cone on the end and piped it into the intake would not really see much gains or none, if anything move the power curve higher into the revs an loose out on lower down torque.

    My point is if your fitting a std b18cr why fit a 3" intake pipe when the std intake system is plenty suficient.
     
  15. B20_R

    B20_R New Member

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    3" is fine even for 2.0 setups.
     
  16. JDMJNKY

    JDMJNKY New Member

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    Good debate.... Good conclusions guys!
     
  17. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    I totally forgot about this thread.

    I remember a magazine that did a big intake shootout like 10 types, it was also put as a online article on one of the mags website. But its hard to find it.

    The comptech gained the most bottom and mid range slightly less peak like 1-2whp compared to the injen within like 300rpms. Thats why I said, it gained the most overall TOTAL HP GAIN.

    Heres a dyno chart i found with 3 intakes slapped on run no tuning.
    AEM Cold Air vs. Injen RD vs. Comptech - Team Integra

    You see the amount of torque/hp on bottom and mid range, comptech wins. This was done on a B18.

    I dont wanna state too much because these intake debates become a pain to argue. Thats why I'm tired of forums. My advice is to research.

    I wont argue that stock intake does well on stock motors. But theres better intakes, thats why they exist.

    When I said mine made peak whp at 9000rpms, I also forgot to mention the power curve is broad. Max torque occured twice on the graph around 4000rpm and again at 7500+ around there approx. So the benefit is, you can rev longer. Because the stock engine makes max HP at 8000 and then drops down towards the limiter. So stock engine is dropping power from 8000, mine is gaining still all the way to 9000rpm and limiter to 9300rpm. Thats quite a difference if you compare HP @ rpms, the difference can be like 10-20whp @ 8500rpm. Means more powerful top end.

    anyway, if a intake does well with no tuning, it can only do better with tuning. You decide.
     
    Last edited: Jul 5, 2010
  18. jugbugz

    jugbugz 1997 EK9 CTR Donator

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    edited

    Even though its a 3.5" pipe + velocity stack, the reducer that attaches the pipe to the TB creates more of a Ram air effect compared to a 3" + reducer. So in theory, the air would have more velocity entering the TB and less air drag and thus creating more instant throttle response with the 3.5" as they all still flow into the same 60mm TB.

    Now you can also take it further by tapering the 60mm to 70mm like the SPOON one which again creates more ram air and increasing the air pressure on the intake mani.

    The reason you upgrade the intake is to modify the way you channel the air into the TB and intake Manifold. Because thats where the limit is unless those parts are changed. But not on a stock motor.

    I had used and dyno'd a modified stock intake with cold air, Js racing intake and now comptech. So I know which is best out of the 3. Best thing about the comptech is, I can remove the ice box cover so it converts to a SRI instantly. But with the ice box cover, the more is way way more consistant with temperature.
     
    Last edited: Jul 5, 2010
  19. krislou80

    krislou80 New Member

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    3" filter would be good. The piping where the filter gets mounted is 3".



    ______________________________________________________________
    K&N 63 SERIES AIRCHARGER COLD AIR INTAKE KIT
    Provides additional power up to 17.54 h.p. at 4917 RPM; 96 to 99 percent filtration efficiency; Includes black roto molded intake tube, red air filter, heat shield, and all the necessary hardware for installation; High-flow intake kit
     
    Last edited: Jul 6, 2010

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